Examining the Association Between the COVID-19 Pandemic and the Rate of Diagnostic Tests for Breast, Cervical, and Colorectal Cancer in Manitoba, Canada.

Background: Strategies to minimize the impact of the COVID-19 pandemic led to a reduction in diagnostic testing. It is important to assess the magnitude and duration of this impact to plan ongoing care and avoid long-lasting impacts of the pandemic. Objective: We examined the association between the COVID-19 pandemic and the rate of diagnostic tests for breast, cervical, and colorectal cancer in Manitoba, Canada. Design and Participants: A population-based, cross-sectional study design with an interrupted time series analysis was used that included diagnostic tests from January 1, 2015 until August 31, 2022. Setting: Manitoba, Canada. Main Outcomes: Outcomes included mammogram, breast ultrasound, colposcopy, and colonoscopy rates per 100,000. Cumulative and percent cumulative differences between the fitted and counterfactual number of tests were estimated. Mean, median, and 90th percentile number of days from referral to colonoscopy date by referral type (elective, semiurgent, urgent) were determined. Results: In April 2020, following the declaration of the COVID-19 public health emergency, bilateral mammograms decreased by 77%, unilateral mammograms by 70%, breast ultrasounds by 53%, colposcopies by 63%, and colonoscopies by 75%. In Winnipeg (the largest urban center in the province), elective and semiurgent colonoscopies decreased by 76% and 39%, respectively. There was no decrease in urgent colonoscopies. As of August 2022, there were an estimated 7270 (10.7%) fewer bilateral mammograms, 2722 (14.8%) fewer breast ultrasounds, 836 (3.3%) fewer colposcopies, and 11 600 (13.8%) fewer colonoscopies than expected in the absence of COVID-19. As of December 2022, in Winnipeg, there were an estimated 6030 (23.9%) fewer elective colonoscopies, 313 (2.6%) fewer semiurgent colonoscopies, and 438 (27.3%) more urgent colonoscopies. Conclusions: In Manitoba, the COVID-19 pandemic was associated with sizable decreases in diagnostic tests for breast, colorectal, and cervical cancer. Two and a half years later, there remained large cumulative deficits in bilateral mammograms, breast ultrasounds, and colonoscopies.

Measuring the impact of COVID-19 on cancer survival using an interrupted time series analysis.

BACKGROUND: Few studies have investigated the impact of the COVID-19 pandemic on cancer survival. Those studies that have included pandemic vs prepandemic comparisons can mask differences during different periods of the pandemic such as COVID-19 waves. The objective of this study was to investigate the impact of the COVID-19 pandemic on cancer survival using an interrupted time series analysis and to identify time points during the pandemic when observed survival deviated from expected survival. METHODS: A retrospective population-based cohort study that included individuals diagnosed with cancer between January 2015 and September 2021 from Manitoba, Canada, was performed. Interrupted time series analyses with Royston-Parmar models as well as Kaplan-Meier survival estimates and delta restricted mean survival times at 1 year were used to compare survival rates for those diagnosed before and after the pandemic. Analyses were performed for 11 cancer types. RESULTS: Survival at 1 year for most cancer types was not statistically different during the pandemic compared with prepandemic except for individuals aged 50-74 years who were diagnosed with lung cancer from April to June 2021 (delta restricted mean survival times = -31.6 days, 95% confidence interval [CI] = -58.3 to -7.2 days). CONCLUSIONS: With the exception of individuals diagnosed with lung cancer, the COVID-19 pandemic did not impact overall 1-year survival in Manitoba. Additional research is needed to examine the impact of the pandemic on long-term cancer survival.